The present invention relates to a device for tensioning core tubes, especially core tubes for webs of paper or similar materials, and consists of several tensioning segments in the shape of arcs of a hollow cylinder that can be displaced radially inside a cage and that are distributed around an arbor, with supports positioned between the arbor and the tensioning segments in circumferential grooves on the surface of the arbor, whereby the cross section of the arbor is an equilateral polygon in the vicinity of the grooves.
Tensioning devices of this type are known, from British Patent No. 917 978 for instance. The supports in the known tensioning devices are cylindrical rollers. When a rotary motion is exerted on the arbor, the cylindrical rollers roll both against the floor of the circumferential grooves in the arbor and against the tubular interior surface of the tensioning segments, forcing the segments radially outward into the tensioning position or inward back into the initial position.
One drawback of the known tensioning device is a high level of wear that results from powerful stress on the arbor, tensioning segments, and cylindrical supports.